From the exhibit and the SC-300 Study Guide (Access Reviews section), the access review is configured with the reviewer type set to (Preview) Manager, and Megan Bowen as the fallback reviewer.
In Azure AD Access Reviews, when "Manager" is selected as the reviewer type, the system automatically assigns each user's Azure AD-defined manager to review their access. However, if a user does not have a manager assigned in Azure AD, the review task defaults to the fallback reviewer (in this case, Megan Bowen).
Therefore, if all access review requests are going to Megan Bowen, that means users in the tenant do not have managers properly assigned in Azure AD user attributes.
Adding the department managers as fallback reviewers does not solve the issue because the fallback reviewer receives only the reviews for users without a manager, not based on department.
Microsoft documentation states:
"When 'Manager' is selected as the reviewer, the manager property from Azure AD is used. If a user does not have a manager, the fallback reviewer is used. Adding managers as fallback reviewers will not assign reviews based on departments."